Stuborn Virus/Malware

I can't seem to shake this virus/malware infections. I have tried all sorts of av and Spyware programs. I have formatted the harddrive and reinstalled xp serveral times. I've wiped the disk using Maxtor's dos zeroing low level format. I've flashed the bios with the latest dell update overwritting a possible flash memory infection.

The problem is the registry appears to be overwritten during boot. I get a Registry Recovery message "One of the files containg the system's registry data had to be recovered by use of a log or alternate copy. The recovery was sucessful." Then a few days go by and we start accumulating all sorts of good stuff (trojans, bad sites visited, malware, etc) Eventually the os crashed and I have to reinstall windows.

I've tried installing a different os like win 2003 servers but the virus seems to disallow certain files from being installed. I though perhaps the windows xp cd I use has the virus but I've installed the same cd on other machines and have not seem this virus.

If anybody has any insight please let me know before I chuck this box onto the highway!